Photonic crystals (PC) are artificial structures comprised of alternate regions of high and low refractive index materials in one, two or three dimensions (3D) that can have a frequency gap or a photonic bandgap where electromagnetic modes are forbidden. In a 3DPC with a suitable geometry and material composition, one can obtain a 3D photonic bandgap where electromagnetic modes in all three dimensions are suppressed, creating an electromagnetic vacuum. See E. Yablonovitch, Phys. Rev. Lett. 58, 2059 (1987); and S. John, Phys. Rev. Lett. 58, 2486 (1987). This property of 3DPCs opens up new regimes of photon manipulation and light-matter interaction.
Inside a photonic bandgap, all radiative emission is suppressed while outside the gap one can obtain enhanced emission due to increased photonic density-of-states. See E. Yablonovitch, Phys. Rev. Lett. 58, 2059 (1987); and T. Suzuki and P. K. L. Yu, Journal of the Optical Society of America B-Optical Physics 12, 570 (1995). 3DPCs can thus make radiative processes preferable to other undesired radiative and non-radiative processes by suitably modifying the electromagnetic environment surrounding an emitter. For example, control of light emission has been previously demonstrated by embedding nano light sources, such as quantum dots, inside 3DPCs. See G. Subramania et al., Applied Physics Letters 95, 151101 (2009); K. Aoki et al., Nature Photonics 2, 688 (2008); C. M. Chuang et al., Journal of Applied Physics 97, 096104 (2005); and P. Lodahl et al., Nature 430, 654 (2004). This property can be particularly useful for enhancing the performance of light-emitting-diodes (LEDs) especially at wavelengths in the green, yellow, and red where efficiency is particularly low. For example, group III nitrides are important semiconductors currently used or being explored for use in LEDs, laser diodes, photo detectors, and photovoltaic devices. Thus far most such efforts involving group III nitrides have focused on two-dimensional photonic crystals (2DPCs) as they are easier to fabricate. For example, group III nitride based 2DPCs have been utilized to improve light extraction efficiencies and to achieve highly directional emission. See J. Wierer et al., Applied Physics Letters 84, 3885 (2004); J.-Y. Kim et al., Applied Physics Letters 96, 251103 (2010); C.-Y. Huang et al., Opt. Express 17, 23702 (2009); P. A. Shields et al., IEEE Journal of Selected Topics in Quantum Electronics 15, 1269 (2009); H. Huang et al., IEEE Electron Device Letters 31, 582 (2010); C. F. Lai et al., Applied Physics Letters 94, 3 (2009); K. McGroddy et al., Applied Physics Letters 93, 103502 (2008); J. Lee et al., Applied Physics Letters 94, 101105 (2009); and T. N. Oder et al., Applied Physics Letters 83, 1231 (2003). However, 2DPCs typically offer light control along only one plane but do not offer complete three-dimensional light control.
Therefore, a need remains for a true 3DPC comprising a direct bandgap semiconductor, such as a group III nitride semiconductor. Integrating 3DPCs with group III nitride or other direct bandgap semiconductor devices according to the present invention will enable new strategies for enhancing the device performance.